Ecophysiological Response of Two Hrebaceous Species to Flooding Implication for Ecological Restoration of Vegetation on Water-level-fluctuating Zone

The capacity and mechanisms of plant species to adapt flooding in ecophysiology is the foundation to select and manage pioneer species in vegetation restoration and reconstruction on water-level-fluctuation zone. We determined experimentally the ecophysiological responses of Polygonum hydropiper and Cynodon dactylon to flooding by simulating flooding. Plants of P. hydropiper were submerged to soil surface and changes of ecophysiological characteristics were tested during its growing season. Plants of C. dactylon were submerged completely and the ecophysiological characteristics were tested during the recovering time. Results showed that the photosynthesis, transpiration of submerged P. hydropiper plants were higher than that of the control plants. Their photosynthetic pigment content of leaves was increased by short-term submersion but decreased by long time submersion. The photosynthesis, transpiration and other physiological activities of submerged C. dactylon plants were also significantly higher than that of the control plants during recovery. The photosynthetic pigment content of leaves was increased with the increasing time. Flooding should be helpful to their growth if the environment of high temperature and drought on the water-level-fluctuation zone were taken into account. C. dactylon and P. hydropiper plants also enhancing its capacity to adapt flooding by developing the adventitious roots and elongating stem. Those results implicate that both of the species have a strong adaptation to flooding and are suitable for the ecological vegetation restoration on the water-level-fluctuation zone in the Three Gorges Reservoir area